1. Field of the Invention
The present invention is broadly directed towards a reinforcer and method of using the reinforcer to reinforce hollow structural members such as those commonly found in vehicles. More particularly, the reinforcer comprises a support having an expansible, synthetic resin reinforcing material attached thereto, wherein the reinforcer is sufficiently flexible or bendable to allow it to negotiate nonlinear or irregular shaped cavities.
2. Description of the Prior Art
During the design and development of automobiles, trucks, aircraft, watercraft, etc., much of the body structure includes hollow cavities, rails, or frame sections. Many times, the structural integrity of the body is improved through increasing the stiffness in localized critical areas. Increased stiffness in these areas generally results in reduced vibration, noise, and/or fatigue propagation. Additional stiffness in these areas has also provided energy management during crash or impact situations.
Many attempts have been made to reinforce these cavities. One such method involves introducing self-sustaining, reinforcing products into the cavity, either with or without a support or carrier structure. However, these methods generally result in the addition of excess weight to the structural member which is undesirable in most instances.
Attempts have also been made to utilize reinforcing products which are lighter in weight or which do not use a support structure, but these attempts usually involve products which lack the necessary strength for properly reinforcing the structural member. Many times the foamable portions of these products do not sufficiently expand upon heating due to the fact that the center of the material is not being properly heated during the activation process. That is, the size of the foam product is sufficiently thick that the core of the product is exposed to minimal heat, thus preventing the core from fully expanding. This can lead to an inadequately reinforced structural member.
Furthermore, many of the structural members that need reinforcement have cavities that are irregular in shape or narrow in size, thus making them difficult, if not impossible, to sufficiently position currently available reinforcing apparatuses therein. For example, the windshield and side pillars on an automobile are typically curved and quite narrow. As a result, currently available reinforcing products generally cannot be passed into the curved, narrow member in the manner necessary to achieve evenly distributed reinforcement along the length of the member. Thus, in order to properly reinforce these pillars, manufacturers must provide parts especially fabricated for a particular pillar. This requires a high degree of manufacturing tolerance and does not allow a single part to be used for a wide variety of hollow structural members.
There is a need for a lightweight, high-strength reinforcing product which is sufficiently versatile to be readily inserted into a wide array of small or irregularly-shaped channels.
The instant invention overcomes these problems by providing a thermally expansible reinforcer for reinforcing a hollow structural member (such as an automobile rail) having a small and/or irregularly shaped cavity.
In more detail, the reinforcing member includes a plurality of pivotally connected sections (such as ball-and-socket connections) with each section comprising a support and a thermally expansible material attached thereto. The support is preferably formed of nylon or metal and each support can be shaped as a tubular, box-like structure which can be used in wide array of cavities. Alternately, one or more of the supports can have a special shape (e.g., pyramidal) to allow the reinforcer to readily enter particularly tight areas.
The reinforcing material is preferably a synthetic, resin-based material which expands when subjected to temperatures achieved at specific points in a manufacturing process (e.g., such as during the paint or powder bake stages of automobile manufacturing processes). This expansion is achieved either by internally created thermal energy or by the external application of heat to activate the material. As used herein, the term xe2x80x9cthermally expansiblexe2x80x9d means both internally created thermal energy and the external application of heat to expand and foam the reinforcing material. The expansion temperature of the material should be at least about 300xc2x0 F.
The inventive reinforcers are particularly useful in that their pivotal connections allow them to be easily fed lengthwise into the opening of a structural member. Furthermore, by utilizing a reinforcer having a number of interconnected sections, reinforcement of the structural member is uniformly distributed over the length of the member.